The union of Hyundai Motor on Tuesday vowed to lay down tools this week, pushing its summer strike streak to a seventh year and adding woes to Korea’s top automaker under multiple whammies from sagging sales at home and threat of steep automobile tariff from the United States.

The Hyundai Motor branch of the militant umbrella trade body Korean Metal Workers’ Union said Tuesday it would walk out for two hours on Thursday if its demands for this year’s collect bargaining - a 5.3 percent, or 116,276 won ($103.71) increase in the base salary, performance-based bonus compensation equivalent to 30 percent of net profit, reinstatement of laid-off workers and other employment terms - are not met.

On Wednesday, shares of Hyundai Motor were down 1.62 percent to close at 121,500 won.

The union is planning another six-hour walkout on Friday in line with its bigger umbrella union’s general strike. Its move came after Hyundai Motor’s management and union failed to reach an agreement after a series of negotiations.

The union held 24 strikes last year and agreed on the wage terms for this year early January after stretching the negotiations onto the following year for the first time.

The union could persuade automakers to take their production elsewhere if it goes on striking against multiple challenges, said an industry observer.